1. Field of the Invention
The present invention relates to a method for year-round utilization of pollinating insects such as bumble bees. To give a more detailed description, the present invention makes it possible for pollinating insects such as bumble bees to be engaged in pollinating activity from January through February, from mid-April through June in the daytime and from July through early September, which are normally inactive periods for such insects in the Northern Hemisphere. In addition, the present invention relates to a constant temperature box which performs temperature control for the nest box to achieve year-round utilization of pollinating insects such as bumble bees.
2. Description of the Related Art
With the development of the apiculture industry, honey bees have been used for pollination of agricultural products. However, there are limits to the utilization of honey bees for the purpose of pollination, such as the fact that they do not visit flowers such as those of tomatoes and eggplants, which do not produce floral nectar, and the fact that they cannot be kept within a small enclosed space. Bumble bees or the like solve these problems concerning pollination.
The utilization of bumble bees for the purpose of pollination was first implemented in Belgium, where they were used for pollination of greenhouse tomatoes. Bumble bees native in Europe (Bombus terrestris) are imported from Europe and used for pollination of tomatoes and the like. According to the present invention, native Japanese species may be used for pollination of tomatoes and the like. The type of nest boxes that are widely employed for housing imported bumble bees in the known art is manufactured using a paper material such as hard board or a plastic material. Such a box is positioned at a strategic location within a greenhouse for growing tomatoes or the like. Typically, a nest box is installed 0.5.about.1 meters above the ground and the temperature inside the nest box is, generally speaking, subject to change in correspondence to changes in the temperature of the outside air. In view of this fact, such measures as installing an awning made of a styrofoam plate on top of the nest box or burying the nest box in the ground have been taken when the temperature becomes high.
Furthermore, there are basically no measures that may be taken against low temperatures in the winter and, normally, bumble bees have not been used for pollination when the temperature is low. In other words, the technology in the prior art does not implement management of the habitat temperature environment in a positive manner but rather it is employed simply to supplement natural mechanisms for adjusting the nest box internal temperature of the nest where bumble bees or the like are housed.
Thus, bumble bees or the like are often exposed to low temperatures or high temperatures that are beyond their capacity for adjusting to the nest internal temperature. By nature, bumble bees or the like form a covering (internal insulating layer) over the contents of the nest to achieve heat preservation when the temperature inside the nest falls below 23.degree. C. and they become active in heat producing activity whereby they produce heat by vibrating their muscles while walking a short distance when the temperature is under 20.degree. C. In addition, when the temperature exceeds 31.degree. C., they attempt to lower the temperature inside the nest by performing ventilating activity.
As a result, when the temperature is under 20.degree. C. or when the temperature exceeds 31.degree. C., individuals who would normally be engaged in pollinating activity outside the nest remain inside the nest to produce heat or to ventilate the nest. Because of this, bumble bees which are capable of performing pollination with the outside air temperature ranging from 5.degree. C. to 37.degree. C. in a natural state can be used for pollination inside a greenhouse only when the temperature is within the range of 10.degree. C. to 28.degree. C. Consequently, they cannot be expected to accomplish much pollination from January through February, from mid-April through June during the daytime, and from July through early September.
Furthermore, with natural nest internal temperature adjustment performed by bumble bees or the like, the life of the colony is reduced due to energy exhaustion in individuals, weakening of physical resources and the death of eggs and larvae when the temperature is too low or too high. In addition, the method that is employed as a countermeasure against high temperatures whereby the nest box is buried underground is not a practical method since, normally, one nest is moved around to serve several greenhouses.